Displaying publications 101 - 120 of 363 in total

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  1. Comparison of thermoregulatory responses to heat between Malaysian and Japanese males during leg immersion
    Wijayanto T, Wakabayashi H, Lee JY, Hashiguchi N, Saat M, Tochihara Y
    Int J Biometeorol, 2011 Jul;55(4):491-500.
    PMID: 20824480 DOI: 10.1007/s00484-010-0358-5
    The objective of this study was to investigate thermoregulatory responses to heat in tropical (Malaysian) and temperate (Japanese) natives, during 60 min of passive heating. Ten Japanese (mean ages: 20.8 ± 0.9 years) and ten Malaysian males (mean ages: 22.3 ± 1.6 years) with matched morphological characteristics and physical fitness participated in this study. Passive heating was induced through leg immersion in hot water (42°C) for 60 min under conditions of 28°C air temperature and 50% RH. Local sweat rate on the forehead and thigh were significantly lower in Malaysians during leg immersion, but no significant differences in total sweat rate were observed between Malaysians (86.3 ± 11.8 g m(-2) h(-1)) and Japanese (83.2 ± 6.4 g m(-2) h(-1)) after leg immersion. In addition, Malaysians displayed a smaller rise in rectal temperature (0.3 ± 0.1°C) than Japanese (0.7 ± 0.1°C) during leg immersion, with a greater increase in hand skin temperature. Skin blood flow was significantly lower on the forehead and forearm in Malaysians during leg immersion. No significant different in mean skin temperature during leg immersion was observed between the two groups. These findings indicated that regional differences in body sweating distribution might exist between Malaysians and Japanese during heat exposure, with more uniform distribution of local sweat rate over the whole body among tropical Malaysians. Altogether, Malaysians appear to display enhanced efficiency of thermal sweating and thermoregulatory responses in dissipating heat loss during heat loading. Thermoregulatory differences between tropical and temperate natives in this study can be interpreted as a result of heat adaptations to physiological function.
    Matched MeSH terms: Tropical Climate/adverse effects
  2. Comparison of heat dissipation response between Malaysian and Japanese males during exercise in humid heat stress
    Wakabayashi H, Wijayanto T, Lee JY, Hashiguchi N, Saat M, Tochihara Y
    Int J Biometeorol, 2011 Jul;55(4):509-17.
    PMID: 20949285 DOI: 10.1007/s00484-010-0374-5
    This study investigated the differences in heat dissipation response to intense heat stress during exercise in hot and humid environments between tropical and temperate indigenes with matched physical characteristics. Ten Japanese (JP) and ten Malaysian (MY) males participated in this study. Subjects performed exercise for 60 min at 55% peak oxygen uptake in 32°C air with 70% relative humidity, followed by 30 min recovery. The increase in rectal temperature (T(re)) was smaller in MY during exercise compared to JP. The local sweat rate and total body mass loss were similar in both groups. Both skin blood flow and mean skin temperature was lower in MY compared to JP. A significantly greater increase in hand skin temperature was observed in MY during exercise, which is attributable to heat loss due to the greater surface area to mass ratio and large number of arteriovenous anastomoses. Also, the smaller increase in T(re) in MY may be explained by the presence of a significantly greater core-skin temperature gradient in MY than JP. The thermal gradient is also a major factor in increasing the convective heat transfer from core to skin as well as skin blood flow. It is concluded that the greater core-skin temperature gradient observed in MY is responsible for the smaller increase in T(re).
    Matched MeSH terms: Tropical Climate/adverse effects
  3. Tropical Malaysians and temperate Koreans exhibit significant differences in sweating sensitivity in response to iontophoretically administered acetylcholine
    Lee JB, Bae JS, Matsumoto T, Yang HM, Min YK
    Int J Biometeorol, 2009 Mar;53(2):149-57.
    PMID: 19048305 DOI: 10.1007/s00484-008-0197-9
    Natives of the tropics are able to tolerate high ambient temperatures. This results from their long-term residence in hot and often humid tropical climates. This study was designed to compare the peripheral mechanisms of thermal sweating in tropical natives with that of their temperate counterparts. Fifty-five healthy male subjects including 20 native Koreans who live in the temperate Korean climate (Temperate-N) and 35 native tropical Malaysian men that have lived all of their lives in Malaysia (Tropical-N) were enrolled in this study after providing written informed consent to participate. Quantitative sudomotor axon reflex testing after iontophoresis (2 mA for 5 min) with 10% acetylcholine (ACh) was used to determine directly activated (DIR) and axon reflex-mediated (AXR) sweating during ACh iontophoresis. The sweat rate, activated sweat gland density, sweat gland output per single gland activated, and oral and skin temperature changes were measured. The sweat onset time of AXR (nicotinic-receptor-mediated) was 56 s shorter in the Temperate-N than in the Tropical-N subjects (P < 0.0001). The nicotinic-receptor-mediated sweating activity AXR (1), and the muscarinic-receptor-mediated sweating activity DIR, in terms of sweat volume, were 103% and 59% higher in the Temperate-N compared to the Tropical-N subjects (P < 0.0001). The Temperate-N group also had a 17.8% (P < 0.0001) higher active sweat gland density, 35.4% higher sweat output per gland, 0.24 degrees C higher resting oral temperature, and 0.62 degrees C higher resting forearm skin temperature compared to the Tropical-N subjects (P < 0.01). ACh iontophoresis did not influence oral temperature, but increased skin temperature near where the ACh was administered, in both groups. These results suggest that suppressed thermal sweating in the Tropical-N subjects was, at least in part, due to suppressed sweat gland sensitivity to ACh through both recruitment of active sweat glands and the sweat gland output per each gland. This physiological trait guarantees a more economical use of body fluids, thus ensuring more efficient protection against heat stress.
    Matched MeSH terms: Tropical Climate
  4. Distribution of detritivores in tropical forest streams of peninsular Malaysia: role of temperature, canopy cover and altitude variability
    Che Salmah MR, Al-Shami SA, Abu Hassan A, Madrus MR, Nurul Huda A
    Int J Biometeorol, 2014 Jul;58(5):679-90.
    PMID: 23483291 DOI: 10.1007/s00484-013-0648-9
    The diversity and abundance of macroinvertebrate shredders were investigated in 52 forested streams (local scale) from nine catchments (regional scale) covering a large area of peninsular Malaysia. A total of 10,642 individuals of aquatic macroinvertebrates were collected, of which 18.22% were shredders. Biodiversity of shredders was described by alpha (αaverage), beta (β) and gamma diversity (γ) measures. We found high diversity and abundance of shredders in all catchments, represented by 1,939 individuals (range 6-115 and average per site of 37.29±3.48 SE) from 31 taxa with 2-13 taxa per site (αaverage=6.98±0.33 SE) and 10-15 taxa per catchment (γ=13.33±0.55 SE). At the local scale, water temperature, stream width, depth and altitude were correlated significantly with diversity (Adj-R2=0.205). Meanwhile, dissolved oxygen, stream velocity, water temperature, stream width and altitude were correlated to shredder abundance (Adj-R2=0.242). At regional scale, however, water temperature was correlated negatively with β and γ diversity (r2=0.161 and 0.237, respectively) as well as abundance of shredders (r2=0.235). Canopy cover was correlated positively with β diversity (r2=0.378) and abundance (r2=0.266), meanwhile altitude was correlated positively with β (quadratic: r2=0.175), γ diversity (quadratic: r2=0.848) as well as abundance (quadratic: r2=0.299). The present study is considered as the first report describing the biodiversity and abundance of shredders in forested headwater streams across a large spatial scale in peninsular Malaysia. We concluded that water temperature has a negative effect while altitude showed a positive relationship with diversity and abundance of shredders. However, it was difficult to detect an influence of canopy cover on shredder diversity.
    Matched MeSH terms: Tropical Climate
  5. Medically important solar ultraviolet A. Radiation measurements
    Ilyas M, Abdul Aziz D, Tajuddin MR
    Int J Dermatol, 1988 Jun;27(5):315-8.
    PMID: 3391727
    Results from a 6-year study of solar ultraviolet A (UVA) radiation measurements at the equatorial location of Penang (5 degrees N) are presented. On clear days, the diurnal flux reaches a very high dosage of about 3.0 x 10(-2) KWHM-2 around midday. The average daily total flux is in the range of 1.6 x 10(-1) KWHM-2 and does not change much seasonally. The high 83% cloud cover only reduces the incoming flux to about half. The radiation flux represents a lower limit of the incident UVA radiation applicable to much of the equatorial/tropical region.
    Matched MeSH terms: Tropical Climate
  6. Fulltext Isolation and Characterization of Aquatic-Borne Klebsiella pneumoniae from Tropical Estuaries in Malaysia
    Barati A, Ghaderpour A, Chew LL, Bong CW, Thong KL, Chong VC, et al.
    Int J Environ Res Public Health, 2016 Apr 15;13(4):426.
    PMID: 27092516 DOI: 10.3390/ijerph13040426
    Klebsiella pneumoniae is an opportunistic pathogen that is responsible for causing nosocomial and community-acquired infections. Despite its common presence in soil and aquatic environments, the virulence potential of K. pneumoniae isolates of environmental origin is largely unknown. Hence, in this study, K. pneumoniae isolated from the estuarine waters and sediments of the Matang mangrove estuary were screened for potential virulence characteristics: antibiotic susceptibility, morphotype on Congo red agar, biofilm formation, presence of exopolysaccharide and capsule, possession of virulence genes (fimH, magA, ugE, wabG and rmpA) and their genomic fingerprints. A total of 55 strains of K. pneumoniae were isolated from both human-distributed sites (located along Sangga Besar River) and control sites (located along Selinsing River) where less human activity was observed, indicated that K. pneumoniae is ubiquitous in the environment. However, the detection of potentially virulent strains at the downstream of Kuala Sepetang village has suggested an anthropogenic contamination source. In conclusion, the findings from this study indicate that the Matang mangrove estuary could harbor potentially pathogenic K. pneumoniae with risk to public health. More studies are required to compare the environmental K. pneumoniae strains with the community-acquired K. pneumoniae strains.
    Matched MeSH terms: Tropical Climate
  7. Fulltext Comparative analysis of Mafriwal (Bos taurus × Bos indicus) and Kedah Kelantan (Bos indicus) sperm proteome identifies sperm proteins potentially responsible for higher fertility in a tropical climate
    Ashrafzadeh A, Nathan S, Karsani SA
    Int J Mol Sci, 2013;14(8):15860-77.
    PMID: 23903046 DOI: 10.3390/ijms140815860
    The fertility of zebu cattle (Bos indicus) is higher than that of the European purebred (Bos taurus) and crossbred (Bos taurus × Bos indicus) cattle in tropical areas. To identify proteins related to the higher thermo-tolerance and fertility of Zebu cattle, this study was undertaken to identify differences in sperm proteome between the high fertile Malaysian indigenous zebu cattle (Kedah Kelantan) and the sub-fertile crossbred cattle (Mafriwal). Frozen semen from three high performance bulls from each breed were processed to obtain live and pure sperm. Sperm proteins were then extracted, and two-dimensional gel electrophoresis performed to compare proteome profiles. Gel image analysis identified protein spots of interest which were then identified by liquid chromatography mass spectrometry quadrupole time-of-flight (LC MS/MS Q-TOF). STRING network analysis predicted interactions between at least 20 of the identified proteins. Among the identified proteins, a number of motility and energy related proteins were present in greater abundance in Kedah Kelantan. Sperm motility evaluation by Computer Assisted Semen Analysis (CASA) confirmed significantly higher motility in Kedah Kelantan. While results from this study do identify proteins that may be responsible for the higher fertility of Kedah Kelantan, functional characterization of these proteins is warranted to reinforce our understanding of their roles in sperm fertility.
    Matched MeSH terms: Tropical Climate
  8. Educational strategies used in increasing fluid intake and enhancing hydration status in field hockey players preparing for competition in a hot and humid environment: a case study
    Dabinett JA, Reid K, James N
    Int J Sport Nutr Exerc Metab, 2001 Sep;11(3):334-48.
    PMID: 11591883
    The purpose of the present study was to develop a hydration strategy for use by female English field hockey players at the 1998 Commonwealth Games in Malaysia. An additional aim was to initiate the process of acclimation. Fifteen elite players, mean age (+/-SEM) 24.1 +/- 1.19 years, height 1.67 +/- 0.01 m, and body mass 62.8 +/- 1.76 kg, took part in a 5-day training camp immediately prior to departure for the Games. In order to develop the hydration strategy, training took place under similar environmental conditions to those to be experienced in Malaysia (i.e., 32 degrees C, 80% humidity). Acclimation training consisted of 30-50 min of either continuous, low intensity cycling or high intensity intermittent cycling, which more closely replicated the pattern of activity in field hockey. Body mass measures taken each morning, and pre and post training, together with urine color measures, were used to assess hydration status. Pre-loading with up to 1 L of a 3% carbohydrate-electrolyte solution or water immediately prior to acclimation training, as well as regular drinks throughout, ensured that players avoided significant dehydration, with percent body mass changes ranging from -0.34% to +4.24% post training. Furthermore, the protocol used was sufficient to initiate the process of acclimation as demonstrated by a significant reduction in exercising heart rate and core temperature at all time points by days 4 and 5. In conclusion, although labor intensive and time consuming, the camp was successful in developing a hydration strategy that players were able to utilize once at the Games.
    Matched MeSH terms: Tropical Climate*
  9. [Tropical monsoon forests of Vietnam (results of 20 years of phytoecological research)]
    Kuznetsov AN, Kuznetsova SP
    Izv. Akad. Nauk. Ser. Biol., 2013 Mar-Apr;?(2):206-16.
    PMID: 23789426
    This study was carried out during the period 1989-2011. The following areas were included: Vietnam, Laos, Cambodia, Indonesia, and Malaysia. Climax tropical forest and anthropogenically transformed ecosystems, including those damaged by the chemical warfare program of the United States in Vietnam, were investigated. Some regularities in the structure dynamics and functioning of forests ecosystems under a tropical monsoon climate have been revealed. The principles of classification of tropical forests have been elaborated. The major results of investigation of the tropical monsoon forests in Vietnam are given.
    Matched MeSH terms: Tropical Climate
  10. Absence of postzygotic isolating mechanisms: evidence from experimental hybridization between two species of tropical sea urchins
    Rahman MA, Uehara T, Arshad A, Yusoff FM, Shamsudin MN
    J Zhejiang Univ Sci B, 2012 Oct;13(10):797-810.
    PMID: 23024047
    Two reef margin species of tropical sea urchins, Echinometra sp. C (Ec) and Echinometra oblonga (Eo), occur sympatrically on Okinawa intertidal reefs in southern Japan. Hybridization between these species was examined through a series of cross-fertilization experiments. At limited sperm concentrations, where conspecific crosses reached near 100% fertilization, both heterospecific crosses showed high fertilization rates (81%-85%). The compatibility of the gametes demonstrated that if gamete recognition molecules are involved in fertilization of these species, they are not strongly species-specific. We found that conspecific crosses reached peak fertilization levels much faster than did heterospecific crosses, indicating the presence of a prezygotic barrier to hybridization in the gametes. Larval survival, metamorphosis, and juvenile and adult survival of hybrid groups were nearly identical to those of their parent species. Hybrids from crosses in both directions developed normally through larval stages to sexually mature adults, indicating that neither gametic incompatibility nor hybrid inviability appeared to maintain reproductive isolation between these species. In adults, Ec×Ec crosses gave the highest live weight, followed by Eo (ova)×Ec (sperm), Ec (ova)×Eo (sperm), and Eo×Eo. Other growth performance measures (viz., test size, Aristotle's lantern length, and gonad index) of hybrid groups and their parental siblings showed the same trends. The phenotypic color patterns of the hybrids were closer to the maternal coloration, whereas spine length, tube-foot and gonad spicule characteristics, pedicellaria valve length, and gamete sizes showed intermediate features. Adult F(1) hybrids were completely fertile and displayed high fertilization success in F(1) backcrosses, eliminating the likelihood that hybrid sterility is a postzygotic mechanism of reproductive isolation. Conversely, intensive surveys failed to find hybrid individuals in the field, suggesting the lack or rarity of natural hybridization. This strongly suggests that reproductive isolation is achieved by prezygotic isolating mechanism(s). Of these mechanisms, habitat segregation, gamete competition, differences in spawning times, gametic incompatibility or other genetic and non-genetic factors appear to be important in maintaining the integrity of these species.
    Matched MeSH terms: Tropical Climate
  11. Inhibition of low-density lipoprotein oxidation and up-regulation of low-density lipoprotein receptor in HepG2 cells by tropical plant extracts
    Salleh MN, Runnie I, Roach PD, Mohamed S, Abeywardena MY
    J Agric Food Chem, 2002 Jun 19;50(13):3693-7.
    PMID: 12059144
    Twelve edible plant extracts rich in polyphenols were screened for their potential to inhibit oxidation of low-density lipoprotein (LDL) in vitro and to modulate LDL receptor (LDLr) activity in cultured HepG2 cells. The antioxidant activity (inhibition of LDL oxidation) was determined by measuring the formation of conjugated dienes (lag time) and thiobarbituric acid reagent substances (TBARS). Betel leaf (94%), cashew shoot (63%), Japanese mint (52%), semambu leaf (50%), palm frond (41%), sweet potato shoot, chilli fruit, papaya shoot, roselle calyx, and maman showed significantly increased lag time (>55 min, P < 0.05) and inhibition of TBARS formation (P < 0.05) compared to control. LDLr was significantly up-regulated (P < 0.05) by Japanese mint (67%), semambu (51%), cashew (50%), and noni (49%). Except for noni and betel leaf, most plant extracts studied demonstrated a positive association between antioxidant activity and the ability to up-regulate LDL receptor. Findings suggest that reported protective actions of plant polyphenols on lipoprotein metabolism might be exerted at different biochemical mechanisms.
    Matched MeSH terms: Tropical Climate*
  12. Fulltext Development and application of a crossbreeding simulation model for goat production systems in tropical regions
    Tsukahara Y, Oishi K, Hirooka H
    J Anim Sci, 2011 Dec;89(12):3890-907.
    PMID: 21705639 DOI: 10.2527/jas.2011-3997
    A deterministic simulation model was developed to estimate biological production efficiency and to evaluate goat crossbreeding systems under tropical conditions. The model involves 5 production systems: pure indigenous, first filial generations (F1), backcross (BC), composite breeds of F1 (CMP(F1)), and BC (CMP(BC)). The model first simulates growth, reproduction, lactation, and energy intakes of a doe and a kid on a 1-d time step at the individual level and thereafter the outputs are integrated into the herd dynamics program. The ability of the model to simulate individual performances was tested under a base situation. The simulation results represented daily BW changes, ME requirements, and milk yield and the estimates were within the range of published data. Two conventional goat production scenarios (an intensive milk production scenario and an integrated goat and oil palm production scenario) in Malaysia were examined. The simulation results of the intensive milk production scenario showed the greater production efficiency of the CMP(BC) and CMP(F1) systems and decreased production efficiency of the F1 and BC systems. The results of the integrated goat and oil palm production scenario showed that the production efficiency and stocking rate were greater for the indigenous goats than for the crossbreeding systems.
    Matched MeSH terms: Tropical Climate*
  13. Biological control of nematode parasites in sheep
    Larsen M
    J Anim Sci, 2006 Apr;84 Suppl:E133-9.
    PMID: 16582084
    In a world in which sheep producers are facing increasing problems due to the rapid spread of anthelmintic resistance, the battle against gastrointestinal parasitic nematodes is a difficult one. One of the potential new tools for integrated control strategies is biological control by means of the nematode-destroying microfungus Duddingtonia flagrans. This fungus forms sticky traps that catch developing larval stages of parasitic nematodes in the fecal environment. When resting spores (chlamydospores) of this fungus are fed daily to grazing animals for a period of time, the pasture infectivity and thus, the worm burden of grazing animals are lowered, especially in young lambs. Research has been conducted throughout the world covering many different climates and management systems. An Australian parasite model showed that if the fungus performs efficiently (> or =90% reduction in worm burden) for 2 or 3 mo, it should contribute significantly to a reduction in the number of dead lambs otherwise occurring when managed only by anthelmintic treatment and grazing management. Feeding or field trials have clearly demonstrated that dosing with a few hundred thousand spores per kilogram of live BW not only reduced the number of infective larvae but also increased the BW of the lambs compared with controls not given fungus. Initial Australian work with feeding spores by means of a block formulation or a slow-release device has shown some promise, but further work is needed to fully develop these delivery systems. In tropical Malaysia, small paddock trials and field studies resulted in significant improvements, in terms of lower worm burdens and increased live BW, when feeding half a million spores daily to grazing lambs. Additional benefits have been observed when the fungus is employed in combination with a fast rotational grazing system. Research has also demonstrated that spores can be delivered in slightly moist feed block material, but only if such blocks are consumed rapidly, because of their very short shelf life. In the northern, temperate Danish climate it has been demonstrated that daily feeding of half a million spores per kilogram of live BW can lead to significant production benefits, with increased live BW gain in fungus-exposed animals. Biological control of parasitic nematodes in sheep seems to hold promise for the future, but to be able to assist producers, the optimal delivery system needs to be refined and further developed. In addition, more work will be needed to define the best use of this technology in different geographic regions.
    Matched MeSH terms: Tropical Climate
  14. Fulltext Genome sequence of Roseomonas sp. strain B5, a quorum-quenching N-acylhomoserine lactone-degrading bacterium isolated from Malaysian tropical soil
    Chen JW, Gan HM, Yin WF, Chan KG
    J Bacteriol, 2012 Dec;194(23):6681-2.
    PMID: 23144419 DOI: 10.1128/JB.01866-12
    Roseomonas sp. strain B5 was isolated from Malaysian tropical soil that showed N-acylhomoserine lactone degradation. This is the first genome announcement of a member from the genus of Roseomonas and the first report on the quorum-quenching activity of Roseomonas spp.
    Matched MeSH terms: Tropical Climate
  15. Effects of reproductive status and high ambient temperatures on the body temperature of a free-ranging basoendotherm
    Levesque DL, Lobban KD, Lovegrove BG
    J. Comp. Physiol. B, Biochem. Syst. Environ. Physiol., 2014 Dec;184(8):1041-53.
    PMID: 25155185 DOI: 10.1007/s00360-014-0858-4
    Tenrecs (Order Afrosoricida) exhibit some of the lowest body temperatures (T b) of any eutherian mammal. They also have a high level of variability in both active and resting T bs and, at least in cool temperatures in captivity, frequently employ both short- and long-term torpor. The use of heterothermy by captive animals is, however, generally reduced during gestation and lactation. We present data long-term T b recordings collected from free-ranging S. setosus over the course of two reproductive seasons. In general, reproductive females had slightly higher (~32 °C) and less variable T b, whereas non-reproductive females and males showed both a higher propensity for torpor as well as lower (~30.5 °C) and more variable rest-phase T bs. Torpor expression defined using traditional means (using a threshold or cut-off T b) was much lower than predicted based on the high degree of heterothermy in captive tenrecs. However, torpor defined in this manner is likely to be underestimated in habitats where ambient temperature is close to T b. Our results caution against inferring metabolic states from T b alone and lend support to the recent call to define torpor in free-ranging animals based on mechanistic and not descriptive variables. In addition, lower variability in T b observed during gestation and lactation confirms that homeothermy is essential for reproduction in this species and probably for basoendothermic mammals in general. The relatively low costs of maintaining homeothermy in a sub-tropical environment might help shed light on how homeothermy could have evolved incrementally from an ancestral heterothermic condition.
    Matched MeSH terms: Tropical Climate
  16. Fulltext The Impact of Heat on Health and Productivity among Maize Farmers in a Tropical Climate Area
    Sadiq LS, Hashim Z, Osman M
    J Environ Public Health, 2019;2019:9896410.
    PMID: 31061664 DOI: 10.1155/2019/9896410
    Background: Heat stress disorders may cause negative health outcome and subsequent productivity reduction especially in those who work under direct sunlight for an extended number of hours.

    Objective: This study assessed the impact of heat on the health and productivity among maize farmers in a hot tropical country.

    Methods: A cross-sectional study was conducted among 396 maize farmers, randomly selected across Gombe province, Nigeria. The wet bulb globe temperature monitor (WBGT) Model QuesTemp036 was used in determining the heat index. Health was determined using a validated questionnaire, while productivity was determined by recording work output based on the number of ridges cultivated during the working hours.

    Results: The farms recorded mean heat index with standard deviation (SD) of 31.56 (2.19) and 34.08 (1.54) in the hours of 9 am to 12 pm and 12-3 pm respectively, which exceeded the threshold level set by the ACGIH. Heavy sweating (93.2%), tiredness (48.5%), dizziness (34.1%), and headache (40.4%) were experienced by the respondents almost on daily basis. The finding further showed a significant difference in the farmers' productivity during the three time duration of the work day (p < 0.001). The productivity was significantly higher between the hours of 6-9 am (p < 0.001) and 12-3 pm (p < 0.001), compared to the hours of 9 am to 12 pm (p < 0.001). The factors that significantly predict the productivity outcome include temperature (p < 0.001), gender (p < 0.001), age (p=0.033), and BMI (p=0.008).

    Conclusion: The farmers were frequently experiencing heat exhaustion which decreased their productivity.

    Matched MeSH terms: Tropical Climate
  17. Trend analysis of a tropical urban river water quality in Malaysia
    Othman F, M E AE, Mohamed I
    J Environ Monit, 2012 Dec;14(12):3164-73.
    PMID: 23128415 DOI: 10.1039/c2em30676j
    Rivers play a significant role in providing water resources for human and ecosystem survival and health. Hence, river water quality is an important parameter that must be preserved and monitored. As the state of Selangor and the city of Kuala Lumpur, Malaysia, are undergoing tremendous development, the river is subjected to pollution from point and non-point sources. The water quality of the Klang River basin, one of the most densely populated areas within the region, is significantly degraded due to human activities as well as urbanization. Evaluation of the overall river water quality status is normally represented by a water quality index (WQI), which consists of six parameters, namely dissolved oxygen, biochemical oxygen demand, chemical oxygen demand, suspended solids, ammoniacal nitrogen and pH. The objectives of this study are to assess the water quality status for this tropical, urban river and to establish the WQI trend. Using monthly WQI data from 1997 to 2007, time series were plotted and trend analysis was performed by employing the first-order autocorrelated trend model on the moving average values for every station. The initial and final values of either the moving average or the trend model were used as the estimates of the initial and final WQI at the stations. It was found that Klang River water quality has shown some improvement between 1997 and 2007. Water quality remains good in the upper stream area, which provides vital water sources for water treatment plants in the Klang valley. Meanwhile, the water quality has also improved in other stations. Results of the current study suggest that the present policy on managing river quality in the Klang River has produced encouraging results; the policy should, however, be further improved alongside more vigorous monitoring of pollution discharge from various point sources such as industrial wastewater, municipal sewers, wet markets, sand mining and landfills, as well as non-point sources such as agricultural or urban runoff and commercial activity.
    Matched MeSH terms: Tropical Climate
  18. Fragmented forest in tropical landscape--the case of the state of Selangor, Malaysia
    Abdullah SA
    J Environ Sci (China), 2003 Mar;15(2):267-70.
    PMID: 12765270
    This paper presents the pattern and changes of fragmented forest in relation with changes of total forest cover in the state of Selangor in three decades. In this study, inventoried forest cover maps of Selangor in 1971/1972, 1981/1982 and 1991/1992 produced by the Forestry Department of Peninsular Malaysia were digitized to examine the changes in area and number of fragmented forest. Results showed that in 1971/1972, 16 fragmented forests were identified in Selangor. All fragmented forests were identified as dipterocarp forest. A decade later the number of fragmented forests increased by approximately 44% (23). Of the 23 fragmented forests, two were peat swamp forests whereas the remaining were dipterocarp forests. In 1991/1992 the number of fragmented forests (12) was reduced by 47.8%. Two of the fragmented forests were identified as peat swamp forest, seven dipterocarp forest and the other three was mixed of dipterocarp forests and plantation forests. Fragmentation of both dipterocarp and peat swamp forests occurred profoundly during the period between 1971/1972 and 1981/1982, which consequently increased the number of fragmented forests compared with before the period of 1971/1972 where fragmentation happened only at dipterocarp forests. However, many fragmented forests vanished between the 1981/1982 and 1991/1992 periods.
    Matched MeSH terms: Tropical Climate
  19. Effects on mice locomotor activity of a narcotic-like principle from Psidium guajava leaves
    Lutterodt GD, Maleque A
    J Ethnopharmacol, 1988 Dec;24(2-3):219-31.
    PMID: 3253493
    Studies were carried out on the suppression of both exploratory and spontaneous locomotor activities in the mouse by a non-polar fraction from a methanol extract of the dried leaves of Psidium guajava. Shortly after intraperitoneal administration of this fraction, typical narcotic-like effects were observed, including catalepsy, analgesia, Straub tail, shallow respiratory movements and exophthalmos. The dose for 90% suppression of exploratory activity was between 3.3 and 6.6 mg/kg intraperitoneally and the onset of action was 6-8 min. The duration of activity was dose-dependent and, for a dose of 13.2 mg/kg given intraperitoneally, it was found to be more than 6 h. Qualitatively similar results on exploratory activity were obtained when the extract was administered orally. Doses of 3.3-6.6 mg/kg i.p. depressed spontaneous locomotor activity and tunnel running was curtailed. Higher doses abolished the spontaneous locomotor reflex action. A flavonoid compound or compounds appear to account for the activity seen.
    Matched MeSH terms: Tropical Climate
  20. Vasorelaxation induced by common edible tropical plant extracts in isolated rat aorta and mesenteric vascular bed
    Runnie I, Salleh MN, Mohamed S, Head RJ, Abeywardena MY
    J Ethnopharmacol, 2004 Jun;92(2-3):311-6.
    PMID: 15138017
    In this study, the vasodilatory actions of nine edible tropical plant extracts were investigated. Ipomoea batatas (sweet potato leaf), Piper betle (betel leaf), Anacardium occidentale (cashew leaf), Gynandropsis gynandra (maman leaf), Carica papaya (papaya leaf), and Mentha arvensis (mint leaf) extracts exhibited more than 50% relaxing effect on aortic ring preparations, while Piper betle and Cymbopogon citratus (lemongrass stalk) showed comparable vasorelaxation on isolated perfused mesenteric artery preparation. The vascular effect on the aortic ring preparations were mainly endothelium-dependent, and mediated by nitric oxide (NO) as supported by the inhibition of action in the presence of N(omega)-nitro-L-arginine (NOLA), an nitric oxide synthase (NOS) inhibitor, or by the removal of endothelium. In contrast, vasodilatory actions in resistance vessels (perfused mesenteric vascular beds) appear to involve several biochemical mediators, including NO, prostanoids, and endothelium-dependent hyperpolarizing factors (EDHFs). Total phenolic contents and antioxidant capacities varied among different extracts and found to be independent of vascular relaxation effects. This study demonstrates that many edible plants common in Asian diets to possess potential health benefits, affording protection at the vascular endothelium level.
    Matched MeSH terms: Tropical Climate
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